Improvement in solar-time instruments



, 2 Sheet s-Sheet 1.

I INVENTOR SWZW ATTORNEY N.FETERS, PHOTO-UTHOGRAPHER, WASHINGTON, a C. l

2 Sheets-Sheet 2. S. HAYFORD. Solar-Time Instrument.

No. 219,469. Patented Spt. 9, I879.

WITNESSES INVE'NTOR C M 7 a. 1. 716UZ/Uv ,ATTORNEY NJETERS.PNOTO-LITHQGRAPRER, WASHINGTON. D Cu UNITED STATES PATENT OFFICE.

SAMUEL HAYFORD, OF AUSTIN, TEXAS.

IMPROVEMENT IN SOLAR-TIME INSTRUMENTS.

y Specification forming part of Letters Patent No. 219,469. datedSeptember 9, 1879; application filed March 28, 1879.

To all whom it may concern:

Be it known that I, SAMUEL HAYFORD, of

Austin, in the county of Travis and State of Texas, have inventedcertain new and useful Improvementsin Solar-Time Instruments; and I dohereby declare the following to be a full, clear, and exact descriptionof the invention,

such as will enable others skilled in the art to which it appertains tomake and use the same, reference being had to the accompanying drawings,and to letters of reference marked thereon, which form a part of thisspecification.

The nature of. my invention consists in the construction and arrangementof a solar-time instrument, as will be hereinafter more fully set forth.

In the annexed drawings, Figure 1 is a perspective view of theentireinstrument. Fi 2 is i a longitudinal section ofone endof thetelescopic tube. Fig. 3 shows the face of the diaphragm with itshorizontal and vertical lines. Fig. at is a central vertical section ofthe instrument.

A represents a base or leveling plate, resting on and operated by threeleveling-screws, B. ()n this, and concentric with it, rests another andsmaller plate, 0, called the azimuthplate, on which are mounted acircular level, 1), and a pair of uprights, F F, each upright supportingone end of a horizontal axis, a. This axis is perforated by and supportsa telescopic tube, G, one end of which holds a lens, 0, the focuswhereof is on the surface of a diaphragm, I, of any suitable material,attached to the other end of the tube.

The diaphragm I has on its surface facing the lens two systems of linescut in the surface, one consisting of two parallel lines, (Z d, invertical planes, intended as a guideto assist in retaining the sunsimage in nearly the same place on the diaphragm during the time cov eredby the observations. The other system of lines is horizontal, andconsists of three, five, or any other desirable number of equidistantparallel lines, 0, placed at such distance that the suns image focusedby the lens shall more than cover the width of the space occupied by thelines.

The axis of the telescopic tube is movable on its own centers inaltitude, and in azimuth by the revolutionof the azimuth-plate on whichits supports rest, so that its optical axis may be set at any angle withthe meridian and the horizon.

By means of screws f at the ends of the axis the telescopic tube may befirmly clamped in any position.

An aperture, h,is made in the side of the tube next the diaphragm,through which the contacts of the suns image with the horizontal linesmay be noted, either with or without the aid of a magnifyingglass; ifwith 'the magnifier, it may be either held in the hand or attachedpermanently as a reading glass to the instrument.

To use the instrument, place it in the sunshine on any tolerably firmsupport, such as a window-sill, and the nearer on the level of the eyethe better, and bring the bubble to the center by means of theleveling-screws. Revolve the upper plate, 0, and the telescopic tube Gon its axis until the image'of the sun is seen just above the horizontallines 6.

Suppose the time to be about 9 oclock a. 111.; see that the bubble is inthe center of the level, and clamp the axis of the telescope; watch theimage of the sun as it descends until its lower edge comes in contactwith the first line, and note the time by a watch; do the same with theother lines as the image moves across the -diaphragm. If great accuracybe required the contacts of the upper edge of the image may also beobserved and the times noted, The instrument is then to be put awaycarefully, being particular not to move the telescopic tube on its axisin the least, as the absolute rigidity of the tube in its position untilthe afternoon obser\ 'ations have been taken is the one condition ofaccurate results.

A little before 3 oclock p. m. the instrument is to be set again in thesunshine. By means of the leveling-screws the bubble is to be brought tothe center, and then the tube directed to ward the sun by revolving theupper horizontal or azimuth plate, but without moving the tube on itsaxis. B y continually directing the tube in thisway toward the sun as itmoves" westward, the suns image will soon be seen entering on the loweredge of the diaphragm and approaching the horizontal lines 6. Now seethat the bubble is stillin the center of the level, and dbserve thecontacts as before,noting the times carefully, and remembering that ifthe lower edge of the image was observed in the morning the same edgemust be observed in the evening, and if both edges were observed in themorning the same should be done in the evening, and in this latter casethe first set of contacts of the morning and the second set of theevening correspond and belong together, and the same of the other twosets.

To calculate the time from one set of observations eachbefore and afternoon, add together the times of the morning contacts, and divide the sumby the number of contacts observed. Do the same by the times of theevening contacts, remembering to call 1. oclock 13 hours, 2 oclock 14hours, and so on. Add together the two average times, and divide the sumby two. The result will be the time of apparent noon by the time-pieceused. This time will need a slight correction, due to the change of thesuns declination in the interval of time between the morning and eveningobservations. This correction is given for every tenth day of the year,and for each degree of latitude from 28 to 49, in a table of equationsto equal altitudes, a copy of which. is to go with every instrument. Theequation of time applied to the corrected time of apparent noon givesthe time of mean noon by the time-piece used. I

I will here give an example of the above. On the 27th of February, 1879,at the city of Austin, Texas, about latitude 30 north, the followingobservations were taken for time:

By referring to the table of equations to equal altitudes it is foundthat the correction for an interval of six hours on the 1st of March inlatitude 30 is a little over eleven seconds, or, say, 11" for 27th ofFebruary, subtractive.

Thus, 12h 24m 24s Less correction, 11

Time of apparent noon, 12 24 13 Add equation of time, 12 58 Gives timeof mean noon, 12 37 11 So that the time-piece used was 37 minutes 11seconds too fast for mean time at Austin.

011 the same occasion the upper limb of the image was observed with thefollowing results:

MORNING. EVENING. 9h 10m 35s upper limb 15h 36m s 9 11 05 15 36 37 9 ll36 15 37 9 12 09 37 40 9 12 37 15 38 12 58 02 78 05 44 ,Divided by 5give 9 11 36' 15 37 08.8 These added make 24 48 45.2 And divided by 2gives 12 2-2 22.6 Less correction, 11

12 22 11.6 Add equation of time, 12 58 Time of mean noon, 12 37 09.6

The two results differ by the amount of 1.4 seconds. Taking the averageor mean result by adding and dividing by 2 gives the true time of meannoon, 12 37 10.3 by the timepiece used.

Some of the advantages of this instrument are, that it is extremelysimple in construction and cannot get out of order by any means short ofabsolute breakage. 'lts construction is such that it requires absolutelyno adjustments previous to being used. Only a few seconds of time arerequired to set it up for use.

Setting up for use consists simply in placing it where'the direct raysof the sun can strike it, and bringing the bubble 'to the center of thelevel by means of the levelingscrews, and

only the simplest possible calculations are required to derive the truetime from the observations.

Having thus fully described my invention, what I claim as new, anddesire to secure by Letters Patent, is-

In a solar-time instrument, the telescopic tube provided at one end witha lens, and at the other end with a removable.diaphragm havinghorizontal and vertical lines marked thereon, in combination with theaxis and clamping device, the azimuth-plate with level and uprightsupports, and the base or bed plate provided with leveling-screws, allconstructed substantially as and for the purposes herein set forth.

In testimony that I claim the foregoing 1 have hereunto setmy hand.

SAMUEL HAYFORD.

Witnesses:

O. W. DANIEL, W. O. SHANDs.

